My cousin just got the gun from his dad as a bday gift. The gun is in great shape, and has a gold trigger if that means anything. I know the Hornady ammo is loaded stronger than others, so is it safe in an older gun ?

I have been shooting 30-30 and 35 Rem Leverevolution out of my to two 70's model 336's without any problems.

Thanks ! Just wanted to make sure he is in the clear

LeverEvolution .30-30 ammo should be safe to fire in any rifle chambered for .30-30, assuming the rifle is in sound condition. Whether or not it will be accurate in any particular rifle will depend on the rifle.